Study Links Maternal Exposure to Lead and Childhood Obesity

An analysis conducted at the Johns Hopkins Bloomberg School of Public Health found an association between maternal exposure to lead, maternal folate status, and intergenerational risk of obese or overweight (OWO) children.

The researchers noted that some experimental studies have suggested that the obesity epidemic could be partially due to chemic exposures during sensitive windows of development, especially in utero and infancy. Lead has well-known fetal toxic effects and multiorgan detrimental associations, and is among the top 10 chemicals of major global public health concern.

Bone lead accounts for 90% of the total body burden and is mobilized during pregnancy and lactation, meaning it is a source of in utero lead exposure. Furthermore, because bone lead stores persist for decades, mothers and infants may be especially at risk for continued exposure.

The cohort study included 1,442 mother-child pairs recruited at birth between October 2002 and October 2013. Maternal lead levels and plasma folate levels were obtained 24 to 72 hours after delivery. Birth weights of the children were obtained from medical records and categorized into small for gestational age (<10^thpercentile), large for gestational age (>90^thpercentile), and appropriate for gestational age (10^th-90^thpercentile).

Of the 1,442 mothers involved in the study, the median maternal red blood cell (RBC) lead level and plasma folate level were 2.5 μg/dL and 32.2 nmol/L, respectively. The median child whole-blood lead level and child BMIzscore was 1.4 μg/dL and 0.78, respectively.

The researchers found that mothers with the highest RBC lead levels were older and multiparous, more likely to be black and nonsmokers, had lower plasma folate levels, and were more likely to have been OWO or diabetic before becoming pregnant.

Children whose mothers had RBC lead levels of at least 5.0 μg/dL had higher whole-blood lead levels in early childhood, and were more likely to be overweight or obese.

The association between maternal RBC lead levels and child BMIzscores remained steady in overweight or obese mothers with low plasma folate levels, but disappeared among overweight or obese mothers with adequate folate status. Children of overweight or obese mothers with high RBC lead levels had a 41% lower risk of being overweight or obese if their mothers had adequate plasma folate levels compared with their counterparts.

The researchers noted that their results need further investigation.

“If further confirmed, they raise the possibility that a combination of prenatal lead screening and optimal maternal folate nutrition may inform a new public health strategy to identify and decrease intergenerational lead toxic effects and overweight/obese risk among US urban low-income popultions,” the report said.

REFERENCE

Wang G, DiBari J, Bind E, Steffens A, et al. (2019).Association Between Maternal Exposure to Lead, Maternal Folate Status, and Intergenerational Risk of Childhood Overweight and Obesity.[online] JAMA Network. Available at:https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2752083[Accessed 3 Oct. 2019].